Synchronizing system



April 29, 1941. l. E. COLE I SYNCHRONIZING SYSTEM 2 sheets-'sheet 1 Filed Aug. 2, 1939 .m 6.3.2 v v /Nl/.E/VTOR [.E. COLE ATTORNEY April 29, 1941. l. E. CQLE 2,239,702

SYNCHRONIZING SYSTEM Filed Aug. '2, 1939 2 sheetssheet 2 SYN.

:MO TOR 'l PERF ORA TOR PERFOR y --W/'TOR I. E. COLE'` 4 TTORNE Y Patented pr. 29, 1941 SYN CHRONIZING SYS TEM Ira E. Cole, Montclair, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York y Application. August 2, 1939, Serial No. 287,925

7 Claims.

This invention relates to communication systems and particularly to means for keeping a pair of distantly separated distributors in exact synchronism with each other. This invention is an improvement in the system disclosed in patent application Ser. No. 219,964, filed July 19, 1938, by Cole et al. now Patent No. 2,207,720, granted July 16, 194:0.

An object of the invention is to provide means for insuring at least one effective transition from spacing to marking per cycle of operation of the distributors in a system wherein the corrected distributor is kept in synchronism with the distant correcting. distributor .through the action of correcting means responsive to transitions from spacing to marking. While communication is being carried on in at least one channel being served by the two distributors, there will always be one or more transitions from spacing to marking per cycle of operation, and while these may occur at random, yet they are effectiveto cause correction.. However, when stoppage of communication occurs on all channels simultaneously, there may be comparatively long periods without a single transition and without an occasional opportunity at correction there is a possibility that the two distributors might fall out of step.

Arrangements have heretofore been provided whereby one or more signals in a complete cycle of operation of such distributors have been inl.

verted so that upon stoppage of communication in all channels there will be one or more transitions from spacing tomarking for correcting purposes. However, such arrangements introduce complications into the circuits and make maintenance more difiicult.

A feature of the present invention is a means for automatically inverting all the signals of one channel, leaving the signals of the other channels undisturbed, when there is stoppage of communication on the said one channel. Then when there is stoppage of communication on all channels there will be at least one effective transition from spacing to marking per cycle of operation of the distributors.

Another feature of the invention resides in a means for disconnecting the code segments of the correcting distributor from the code transmitter and connecting them automatically to a source of marking battery so that when stoppage of communication occurs on the one channel so equipped, a steady stream of marking signals will be transmitted in place Vofv the steady stream of spacing signals.

`Another feature is the use 4of ataut tape switch d for causing the changeover from spacing to mark.

ing during stoppageof communication as sig-y nalized by the tightening of vthe tape.

Still vanother feature is the use of a double Wound multicontact relay for causing the automatic changeover from steady spacing to steady marking. The two windings, of the relay are arranged to oppose andv neutralize each other so that when an impulse is periodically vtransmitted to such rel-ay'once per cycle of operation of the correcting distributor it will be ineffective unless one winding of the relay is opened by the taut tape switch. The relay then locks up and remains in this condition until the taut tape switch again closes its contact whereupon the two windings of such relay neutralize each other and the relay releases the circuit to its normal condition.

The drawings consist of two sheets, comprising 20.1 Fig. 1 in the form of a block schematic diagram,

and Fig. 2, a circuit diagram illustrating the invention. With Fig. 2 placed above Fig. 1, a complete diagram illustrating the invention is formed.

Fig. 1 is a general schematic of a system in which the invention may be employed. A speech path I leads to a hybrid coil 2 from which a path 3 for outgoing speech leads to a vogad 4. The outgoing speech then passes through a transmitting suppressor 5 and by means of an amplifierdetector 6 operates a chain of relays l, here labeled as voice operated switching circuit. This voice operated switching circuit controls a transmitting singing suppressor 9 so that the outgoing speech can pass from the transmitting lsuppressor 5 through the delay and amplifier 8 and the transmitting singing suppressor 9 tothe hybrid coil l0. From the hybrid coil I il the speech reaches another hybrid coil H and thence goes through the radio transmitter to an antenna I3. Through radio transmission, the speech will be received at some distant point and for purposes. of explanation it will be assumed that the distant point has a receiving circuit similar in all respects to the lower part of Fig. 1. The speech, therefore, enters antenna I4, passes through a radio receiver l5 and a repeater I6 to a hybrid coil I1. From the hybrid coil Il the speech goes into hybrid coil I8, thence through the receiving singing suppressor I9,`

the receiving repeater 20, a low-pass filter 2l and a path 22 to a hybrid coil, such as 2v, whence "it goes to the receiving subscriber over a line,-such as I.

The voice operated switching circuit 'I controls a control tone enabler 2'3 through the contact and armature of the relay 83 so that a source of control tone 24 is passed through the control tone compressor |26 and the control tone filter 25 to the hybrid coil II and thus accompanies speech. The voice operated switching circuit 1 also controls a switching point leading from the receiving switching circuit 26 at the same terminal to the transmitting suppressor so as to open this circuit during the periods that speech is going out from line I to antenna I3. During this time the voice operated switching circuit 1 also controls the telegraph control circuit shown in Fig. 2 by operating relay |04 in order to stop the action of the telegraph transmitting circuit during the time the voice is being transmitted from line I out over antenna I3.

At the receiving end the control tone with the usual modulation of the carrier frequency coming in over antenna I4 is dernodulated in radio receiver I5 and passes through the hybrid coil I1 and thence through a telegraph band elimination lter 28 and into a control tone amplifier and filter 29. This operates the receiving switching circuit 2S which performs several functions as follows: first, the receiving switching circuit 26 controls a normally open circuit between the telegraph band elimination filter 28 and the receiving switching circuit 26, including a speech amplifier 30 so that when control tone is first received the switching circuit 26 will be operated thereby and then held operated thereafter by speech currents flowing through the amplifier 3D. When the control tone is first transmitted it goes out into antenna I3 at high volume but after an interval determined by the delay introduced by the delay and amplifier 8 the speech operates a compressor IZB to reduce the volume of the control tone to avoid overloading the radio transmitter I2 by the combination of control tone and speech. This, of course, operates to advantage at the receiving end by giving an impulse of great strength through the control tone amplifier and filter 29 to operate the circuit 26 before the path through the speech amplifier 30 is closed.

The receiving switching circuit also controls the receiving singing suppressor I9 to open up the speech path. The receiving switching circuit 26 also controls a normally closed path between the band-pass filter 3i and the telegrad 32 so that, while speech is being received, the telegrad 32 will be disabled. At the same time, the receiving switching circuit 26 controls the switching relay 33 for two telegraph channels.

During pauses in the speech, either when the subscriber at the distant end is talking into channel I or during the time when the subscriber on channel I pauses during histalk out over the antenna I3, the telegraph apparatus shown in Fig. 2 is in operation. This comprises perforators 6I and 35 working respectively into tape transmitters 63 and 95 and thence into the rotary distributor shown in the upper right-hand corner of Fig. 2 and here designated generally by the numeral 64, indicating the motor and synchronous equipment for driving such distributor. The rotary distributor works through the control circuit comprising various relays of Fig. 2 and by means of relay 19 controls the telegraph signal converter 39. This signal converter is a circuit controlling device disclosed in Patent 1,749,851 to H. C. Silent, March 11, 1930. When the relay 19 is on its marking contact, then the telegraph signal suppressor is in such a condition that alternating current coming from the telegraph signal oscillator 46 passes freely into hybrid coil I6 for transmission out over the antenna I3. When the relay 19 has its armature driven to its spacing contact, then the suppressing action of the telegraph signal converter 39 blocks oi the telegraph signaling current and no current will, therefore, get into hybrid coil I0.

At the distant end these telegraph signals in the form of spurts of alternating current of the usual form of a carrier of the oscillator frequency with side-bands about seventy cycles wide caused by the modulation of the carrier by the telegraph transmitter are received over antenna I4 by the radio receiver I5 and thence through the repeater I6 whence they pass through the hybrid coils I1 and I8 to the band-pass filter 3|.

`Thereafter the signals enter the telegrad 32 and are converted from varying strength alternating current signals to uniform strength direct currentsignals of practically the same strength at which they were received over the antenna I4. For a complete description of the telegrad, reference is made to application Serial No, 283,368, led July 8, 1939, by Barney et al. These direct current signals then pass through the switching relay circuit 33 and the rotary distributor 4I to the two printers 42 and 43. During the reception of telegraph signals the receiving switching circuit 26 is unoperated and the speech path is blocked ofi by the receiving singing suppressor I9.

The rotary distributor 4l is kept in synchronism with the distant rotary distributor whose shaft 65 is rotated by th-e rotor 64 and which is shown in the upper right-hand corner of Fig. 2 by means generally described in the Cole et al. Patent No. 2,207,720 and in particular by the means disclosed in a patent granted to L. A. Meacham No. 2,207,748, granted July 16, 1940.

For purposes of the present description, it is only necessary to mention the fact that the rotary distributor 4I will be kept in perfect synchronism with the distributor of Fig. 2 if there is an occasional transition from a spacing to a marking impulse, that is, if there is an occasional operation of the relay 19. Such transitions are caused during the normal operation of either the A channel or the B channel, here represented by tape transmitters 63 and 95, respectively. If there is a stoppage of transmission over both channels at the same time so that neither transmitter 63 nor transmitter 95 is in operation, then the novel means of the present invention provided to cause an occasional operation of the relay 19- Specially, as shown, the relay 19 will go through one cycle of operations per cycle of operation of the rotary distributor of Fig. 2.

In operation, if no voice currents are being transmitted from line I and the voice operated circuit, therefore, is unoperated, the telegraph apparatus of Fig. 2 will be fully enabled with relay m4 in the position shown.

The tape transmitter 63 has five pins, such as 13, which will engage perforations in the tape 62. When this occurs, the contact 14 is moved from its lower contact 15 to its upper contact 16. The upper contact 16 represents a marking condition and the lower contact 15 represents a spacing condition. When in the course of operation of the distributor the shaft 65 brings a brush into position to make the contact between segment 'I1 and ring 13, either spacing current from contact 15 or marking current from contact 16 will be extended through the .telegraph transmitting line relay 19. If marking current is transmitted, then the polar relay 19 will be left in the position shown, whereby the secondaries of transformers S4 and '55vare closed and the tone from source 4E! is transmitted into the hybrid coil I and thereafter out over antenna I3. If spacing current is transmitted through the relay 19, then the armature will move to the left and the telegraph signal converter 39 will prevent any tone being transmitted into the hybrid coil l0, thus establishing a spacing signal condition.

Let us assume that the shaft 155 is just coming .to a position where it will make a connection from segment 8@ to ring 8l and where the brush Worlnng on ring 18 will successively pass over the Vsegments 32', 83, 8d, 85 and 11, comprising the ve code segments from the channel A transmitter. Under the assumption that the voice circuit is not being used at this time, the relays 85, 81, 8S and 89 will be in the positions shown. As just previously mentioned, a connection has been made between ring Si@ and segment 9|', thus connecting ground to the lower Winding of relay 92. to 'the position shown so that battery is connected to one side of the stepping magnet 93 in the channel A tape transmitter 63. This magnet is not energized at this time. Since relay 81 is in the position shown, the connection between cornmon ring 3! and segment S0 is ineiTec-tive and, therefore, relay 92 is left in the position shown. Now, as the brush successively passes over segments 32, 33, te, 85 and 11, the marking or spacing signal current, as the case may be, is transmitted through the back contact and armature of relay rit t0 the contact and armature of relay 8E, winding of relay 1Q, to the common point of the marking and spacing batteries.

As the brushes connected to shaft 65 pass further along and are now in the position of transferring the record from tape transmitter S5, a connection will be made from ring 96 to segment 91 and thence to the other sideof stepping magnet 93 so that, while the record from tape transmitter 95 is being transmitted, the shaft of tape transmitter S3 will be rotated and the tape advanced to the next set of code perforations. In a similar manner, during the movement of the shaft 65, a connection will be made to segment 59 while the record from tape transmitter' 63 is being transmitted and shaft lill) will be rotated through the energization of magnet |01. In this manner the record of the two transmitters will be alternately transmitted by the relay 19.

Let it be assumed now that there is a stoppage oi transmission over the B channel. This means that the tape 34 will become taut and the taut tape switch 36 will operate to open the circuit between the left-hand winding of relay 31A and conductor 38. Prior to the operation of taut shape switch 36, a connection will be made between ring 9b and segment 21 once per cycle of operation of the rotary ydistributor and at a time just after the brush has left the segment `99.

This results in the placing of ground `on'the conductor 38 leading in parallel to the two windings oi' relay 31. These windings, however, are equalv and opposed so that the relay 31 does not become operated at this time. However, when the taut tape switch 36 is operated, then the next time that connection is made between the ring Qt and the'segment 21 the right-hand Winding of relay 31 alone Will be energized and, since there is now no opposing force, the relay 31 will operate and through its right-hand armature and lfront contact will lock in an operated position. The left-hand armatures of this multicontact relay 31 now transfer the tape transmitter Relay .92 will then have moved its contact contacts from the distributor contacts '56, 51, 58,

5S and. 60 to conduct-or 44, leading to the markf brush on shaft 65 is passing `over segments' 56 to Gil, inclusive.

If during this time the channel A becomes idle, then spacing current will be connected to the segments 82, 33, at, '85 and 11 and hence the telegraph transmitting line relay 19 will send out first five spacing signals and then ve marking signals and will repeat this operation as long as there is stoppage of transmission on both channels. Thus, there will be at least one transition from a spacing to a marking impulse per cycle of operation of the rotary distributor.

When transmission is resumed on channel B, Ithe perforation or" more tape will cause the taut tape switch Sii to operate to the position shown, hence, when the brush of the rotary distributor again makes contact between ring 9S and segment 21, the left-hand winding of relay 31 will be energized. Since the right-hand winding is already energized, the result will be equal and i proper transmission of the codes will take place.

i The operations of the relays @t to 39, inclusive, are fully explained in the Cole et al. application Ser. No. 219,964. g In general, when the voice takes command of the circuit and the voice operating circuit 1 is operated, then relay I M becomes operated and, in turn, causes the operation of relays Sii and 81. Thereupon the transmission of. telegraph signals is stopped through the operation of relay 92 and its companion relay E05, which prevent the operation of the stepping magnets g3 and il, respectively.

rIf the transmission of code is at a critical point, as when a connection is being made be-l tween ring m8 and segment H01, the relays 88 and 89 will be operated so as` to prevent the operation of relay lilli from operating' the relays Et and 81 to stop the transmission of a telegraph code. This condition, however, lasts for only a very short interval and relays 383 and 89 will return to normal so tha-t relays 86 and 81 may become operated in the usual manner.

It is to be understood that the present invention is not limited in its application to the interpolated telephone and telegraph system above described but may with equal usefulness' be incorporated 'in any telegraph system wherein a distant distributor is to be kept in synchronism with a near distributor through the method of correcting bytransitions from spacing to marking conditions.

What is claimed is: Y

1. In a synchronizing system, a correcting olistributor, a corrected distributor, a plurality of communication channels served over said 'distributors, correcting means responsive to transitions `from one type of communication signal cornmunication channels served over said distributors, correcting means responsive to transitions from one type of communication signal to another type of communication signal, means associated with one of said communication channels for indicating stoppage of communication over said channel, and means responsive to said last means for changing the character of the sig nals over said channel during stoppage of communication whereby there will be at least one transition of communication signal type per cycle of operation of said distributors.

3. In a synchronizing system, a correcting distributor, a corrected distributor, a plurality of communication channels served over said distributors, means for communicating over said channels by permutations of diierent electrical conditions, said last means including means for continuously transmitting one of said electrical conditions over said channels during stoppage of communication thereover, correcting means responsive to transitions from one electrical condition to another', means associated with one of said communication channels for indicating stoppage of communication thereover and means responsive to said last means for changing said continuous transmission of one of said electrical conditions to continuous transmission of another of said electrical conditions, whereby under condition of stoppage of communication on all said channels there will be at least one eiective transition from one condition to another per cycle of operation or said distributors for operating said correcting means.

4. In a synchronizing system, a correcting distributor, a corrected distributor, a plurality of communication channels served over said distributors, a plurality of code segments on said distributors `for each said channel, means for alternatively placing marking or spacing conditions on said segments for communicating by permutation codes, means during stoppage or communication over any one channel for placing spacing condition on all code segments of said channel, correcting means at the said corrected distributor responsive to transitions from one condition to another, means associated with one of said communication channels at the correcting distributor for indicating stoppage of communication over said channel, and a multicontact relay responsive to said last means for placing marking condition on all code segments of said channel whereby under condition of stoppage or communication on all said channels there will be at least one eiective transition from spacing to marking per cycle of operation of said distributors for operating said correcting means.

5. In a synchronizing system, a correcting distributor, a corrected distributor, a plurality of communication channels served by said distributors, a plurality of code segments on said distributors for each said channel, a transmitter for each channel for communicating over said channel by permutations of marking and spacing conditions placed on the code segments of said channel, said transmitter placing spacing conditions on all code segments of its channel during idle periods thereof, correcting means at the said corrected distributor responsive to transitions from one condition to another, means associated with one of said transmitters responsive to the idle condition thereof, and a multicontact relay responsive to said last means for placing marking condition on all code segments of said channel whereby under condition of stoppage of communication on all said channels there will be at least one effective transition from spacing to marking per cycle of operation of said distributors for operating said correcting means.

6. In a synchronizing system, a correcting distributor, a corrected distributor, a plurality of communication channels served by said distributors, a plurality of code segments on said dis'- tributors for each said channel, a tape transmitter lfor each channel for communicating over said channel by permutations of marking and spacing conditions placed on the code segments of said channel, said transmitter placing spacing conditions on all code segments of its channel during idle periods thereof, correcting means at said corrected distributor responsive to transitions from one condition to another, a taut tape switch associated with one of said transmitters, and a multicontact relay responsive to said taut tape switch for placing marking condition on all code segments ofsaid channel whereby under condition of stoppage of communication on all channels there Will be at least one effective transition from spacing to marking per cycle of operation of said distributors for operating said correcting means,

7. In a synchronizing system, a correcting distributor, a corrected distributor, a plurality of communication channels served by said distributors, a plurality of code segments on said distributors for each said channel, a tape transmitter for each said channel for communicating over said channel by permutations of marking and spacing conditions placed on the code segments of said channel, said transmitter placing spacing conditions on all code segments of its channel during idle periods thereof, a stepping segment for each channel on said correcting distributor for advancing the tape in said transmitter, correcting means at said corrected distributor responsive to transitions from one condition to another, a taut tape switch associated with one of said transmitters, a multicontact relay for placing marking condition on allY code segments of said channel, said relay having tWo equal and oppositely acting windings thereon, one of said windings being included in the circuit of said taut tape switch, and means including another segment on said correcting distributor for closing the circuit of said relay once per cycle of operation of said distributor, whereby said circuit closing means is eiective to energize said relay when one Winding is opened by said taut tape switch, and is effective to deenergize said relay when said one winding is closed by said taut tape switch, whereby under condition of stoppage of communication on al1 channels there will be at least one effective transition from spacing to marking per cycle of operation of said distributors for operating said correcting means.

IRA E. COLE. 

